(1)
Except as provided in Sentence (2), where an upper roof, or part thereof, slopes downwards with a slope α > 0 towards a lower roof, the snow load, S, on the lower roof, determined in accordance with Articles 4.1.6.2. and 4.1.6.5., shall be augmented in accordance with Sentence (3) to account for the additional load resulting from sliding snow.
(2)
Sentence (1) need not apply where
(a)
snow from the upper roof is prevented from sliding by a parapet or other effective means, or
(b)
the upper roof is not considered slippery and has a slope less than 20°.
(3)
The total weight of additional snow resulting from sliding shall be taken as half the total weight of snow resulting from the uniform load case prescribed in Article 4.1.6.2. with
(a)
the accumulation factor Ca = 1.0 for the relevant part of the upper roof,
(b)
the slope factor, Cs, based on the slope of the lower roof, as prescribed in Sentences 4.1.6.2.(5) and (6), and
(c)
the sliding snow distributed on the lower roof such that it is a maximum for x = 0 and decreases linearly to 0 at x = xd, as shown in Figure 4.1.6.11., where x and xd are as defined in Article 4.1.6.5.
Figure 4.1.6.11. Snow Distribution on Lower Roof with Sloped Upper Roof
Forming Part of Sentence 4.1.6.11.(3)
